A silicon process, where an electronic circuit can be constructed and an inexpensive and large-scale integration technique is in progress, may be applied to an optical device. Application of the silicon process to the optical device can materialize a large-scale optical system which includes a driver and an inexpensive optical device by mass production. An optical device may be used for an optical communication network, an optical interconnection, and so on.
In a silicon optical integrated circuit chip being one of optical devices, elements such as an optical modulator, a light receiver, and a passive element are formed at a high density on a silicon substrate. A driving circuit chip is connected to the silicon optical integrated circuit chip and the driving circuit chip is connected to a circuit board. Conventionally, a bonding wire is used in part of such connection, and thus it is difficult to materialize a high-speed operation and high integration of multiple channels.
It is also discussed to mount a silicon optical integrated circuit on a mount board such as a circuit board processed into a predetermined shape while the silicon optical integrated circuit being connected to the mount board with a flip chip bump. However, in the prior art, it is required to process the mount board at a high accuracy, materialization of which is difficult and which leads to cost increase. In other words, loose connection occurs when a processing accuracy is not high, and thus modularization is difficult.    Patent Literature 1: Japanese Patent No. 3371954    Patent Literature 2: Japanese Laid-open Patent Publication No. 2011-107206    Patent Literature 3: Japanese Laid-open Patent Publication No. 2007-249194    Non-Patent Literature 1: Pan et al., Opt. Express, Vol. 20(16), 18145-18155    Non-Patent Literature 2: Zheng et al., J. Lightwave Technology, 2012, Vol. 30(4), 641-650